CN113714634A

CN113714634A - Laser processing system and method

Info

Publication number: CN113714634A
Application number: CN202010450845.6A
Authority: CN
Inventors: 蒋峰; 杨德权; 张均; 雷剑; 吕张勇; 郝冀; 王英
Original assignee: Maxphotonics Co Ltd
Current assignee: Maxphotonics Co Ltd
Priority date: 2020-05-25
Filing date: 2020-05-25
Publication date: 2021-11-30
Anticipated expiration: 2040-05-25
Also published as: CN113714634B

Abstract

The embodiment of the invention provides a laser processing system and a method, wherein the system is used for generating composite laser output to a workpiece and comprises a laser and a laser processing head; the laser is used for providing composite laser light with at least one first light beam and a second light beam; the laser is provided with an optical fiber, and the laser processing head is connected with the optical fiber and used for guiding the composite laser output by the laser to the workpiece. The embodiment of the invention has the advantages of less used devices, low cost and good processing effect.

Description

Laser processing system and method

Technical Field

The present invention relates to the field of laser technology, and in particular, to a laser processing method and a laser processing system.

Background

With the rapid development of the manufacturing technology of the optical fiber and the semiconductor laser, the output power of the optical fiber and the semiconductor laser is greatly increased, and a feasible solution direction can be provided for high-quality precision machining by utilizing a composite machining technology of splitting single laser or compounding a plurality of lasers into two beams or a plurality of beams of lasers.

In one existing solution, two laser devices are used, and the two laser devices output light beams through two optical fibers through a composite processing head. The cost is high due to the fact that two laser devices and optical devices for beam combination are needed, the reliability hidden danger is caused due to the fact that the complexity of optics and control of the whole system is greatly increased, the size of the system is too large, the system is limited in some special application scenes, and the flexible processing capacity of the composite laser is weakened.

Disclosure of Invention

In view of the above problems, embodiments of the present invention are proposed to provide a laser processing method and a corresponding laser processing system that overcome or at least partially solve the above problems.

In order to solve the above problems, an embodiment of the present invention discloses a laser processing system for generating a composite laser output to a workpiece, including a laser and a laser processing head;

the laser is used for providing composite laser light with at least one first light beam and a second light beam;

the laser is provided with an optical fiber, and the laser processing head is connected with the optical fiber and used for guiding the composite laser output by the laser to a workpiece.

Optionally, the apparatus further comprises a control device for adjusting the power of the first beam to adjust the spot energy distribution of the first beam on the workpiece and/or adjusting the power of the second beam to adjust the spot energy distribution of the second beam on the workpiece.

Optionally, the control device is further configured to control the power value of the first beam and the power value of the second beam according to a material of the workpiece.

Optionally, the control device is further configured to adjust the defocus amount of the first beam to adjust the spot profile and energy distribution of the first beam irradiated to the workpiece, or adjust the defocus amount of the second beam to adjust the spot profile and energy distribution of the second beam irradiated to the workpiece.

Optionally, the laser processing head is provided with a single fibre joint through which the fibre of the laser is adapted at the laser processing head to direct the first and second beams onto the workpiece.

Optionally, the laser has a single laser module, and the single laser module is configured to transmit pump light that is not absorbed in a fiber cladding to form a first light beam, and transmit signal light amplified in a fiber core to form a second light beam.

Optionally, the laser has a single laser module, and the single laser module is configured to transmit pump light that is not absorbed in a fiber cladding and signal light that leaks into the cladding to form a first light beam, and transmit amplified signal light in a fiber core of the optical fiber and pump light that leaks into the fiber core to form a second light beam.

Optionally, the laser is a single resonant cavity laser or a MOPA laser.

Optionally, the wavelength of the first light beam is different from the wavelength of the second light beam, the central wavelength of the second light beam is 1030-.

Optionally, the central wavelength of the first light beam is 915nm, and the central wavelength of the second light beam is 1080 nm.

The embodiment of the invention also discloses a laser processing method, which comprises the following steps:

irradiating laser light having at least a first beam and a second beam onto a surface of a workpiece; the first light beam irradiates the workpiece to form a first light spot, the second light beam irradiates the workpiece to form a second light spot, the second light spot is located in the first light spot, and the energy of the second light spot and the energy of the first light spot are adjustable.

Optionally, the energy distribution of the first light beam is in a flat-top distribution, and the energy distribution of the second light beam is in a gaussian distribution.

Optionally, the method further comprises: and adjusting the power value of the first light beam to adjust the energy distribution of the light spot irradiated to the workpiece by the first light beam, and/or adjusting the power value of the second light beam to adjust the energy distribution of the light spot irradiated to the workpiece by the second light beam.

Optionally, the method further comprises: and controlling the power value of the first light beam and the power value of the second light beam according to the material of the workpiece.

Optionally, the method further comprises: and adjusting the defocusing amount of the first light beam to adjust the spot profile and the energy distribution of the first light beam irradiated to the workpiece, or adjusting the defocusing amount of the second light beam to adjust the spot profile and the energy distribution of the second light beam irradiated to the workpiece.

Optionally, the irradiating the laser light having at least one first beam and a second beam onto the surface of the workpiece includes:

the method comprises the steps of transmitting unabsorbed pump light and signal light leaking into a cladding in an optical fiber cladding of a laser to form a first light beam, and transmitting amplified signal light in an optical fiber core and pump light leaking into the fiber core to form a second light beam.

the first beam and the second beam are directed to a workpiece by a single fiber splice laser processing head.

Optionally, the wavelength of the first light beam is different from the wavelength of the second light beam, the central wavelength of the first light beam is 915-.

The embodiment of the invention has the following advantages:

the laser processing system of the embodiment of the invention provides composite laser with at least one first beam and at least one second beam through a laser; the laser has an optical fiber, and the laser processing head is connected with the optical fiber and is used for guiding the composite laser output by the laser to a workpiece. The first light beam can be used for preheating the surface of the workpiece to form a smooth molten pool, and the second light beam is used for forming a keyhole in a preheated area on the surface of the workpiece, so that the greater penetration is obtained, and the processing effect is good. The two light beams are combined without using an additional composite welding head, so that the processing cost can be reduced. And because the first light beam and the second light beam are transmitted in the same optical fiber, the processing direction principle has no requirement, and the processing technology can be simplified.

Drawings

FIG. 1 is a flow chart of the steps of one embodiment of a laser machining method of the present invention;

FIG. 2 is a schematic diagram of a composite laser energy distribution in an actual state;

FIG. 3 is a schematic diagram of a composite laser energy distribution in an ideal state;

FIG. 4 is a schematic diagram of another composite laser energy distribution under ideal conditions;

FIG. 5 is a schematic diagram of another composite laser energy distribution under ideal conditions;

FIG. 6 is a schematic diagram of another composite laser energy distribution under ideal conditions;

FIG. 7 is a block diagram of a laser processing system embodiment of the present invention;

FIG. 8 is a block diagram of a laser in an embodiment of the invention;

FIG. 9 is a block diagram of a laser in one example;

fig. 10 is a block diagram of a laser in another example.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

Referring to fig. 1, a flowchart illustrating steps of an embodiment of a laser processing method of the present invention is shown, which may specifically include the following steps:

step 101, irradiating laser with at least one first beam and a second beam on the surface of a workpiece; the first light beam irradiates the workpiece to form a first light spot, the second light beam irradiates the workpiece to form a second light spot, the second light spot is located in the first light spot, and the energy of the second light spot and the energy of the first light spot are adjustable.

At least one of the first beam and the second beam may be directed to the workpiece by a single fiber splice laser processing head.

In this embodiment of the present invention, the step 101 may include the following sub-steps:

in sub-step S11, unabsorbed pump light in a fiber cladding of a laser is transmitted to form a first beam, and amplified signal light in a core of the fiber is transmitted to form a second beam.

Specifically, unabsorbed pump light in a fiber cladding of a laser and signal light leaking into the cladding can be transmitted out to form a first light beam, and amplified signal light in a fiber core of the fiber and pump light leaking into the fiber core can be transmitted out to form a second light beam;

the unabsorbed pump light and the signal light leaking into the cladding from the core may be transmitted in the cladding of the optical fiber, and the amplified signal light and the pump light leaking into the core from the cladding may be transmitted in the core of the optical fiber.

The sub-step S11 may further include:

substep S111, transmitting the amplified signal light in a core of an active optical fiber, and transmitting the unabsorbed pump light in a cladding of the active optical fiber;

and a sub-step S112 of transmitting the pump light unabsorbed in the cladding of the active optical fiber and the signal light leaking into the cladding from the core to form a first light beam, and transmitting the amplified signal light in the core of the active optical fiber and the pump light leaking into the core from the cladding to form a second light beam.

The laser may further include a passive optical fiber connected after the active optical fiber, and the substep S112 may further include:

a substep S1121 of transmitting the pump light output from the cladding of the active fiber and the signal light leaking into the cladding from the core in the cladding of the passive fiber connected to the active fiber, and transmitting the amplified signal light output from the core of the active fiber and the pump light leaking into the core from the cladding in the core of the passive fiber;

when the number of claddings of a passive fiber connected to the active fiber is greater than that of the active fiber, pumping light output from the claddings of the active fiber and signal light leaking into the claddings from the core are transmitted into at least one of the claddings of the passive fiber.

In sub-step S1122, the pump light not absorbed in the cladding of the passive fiber and the signal light leaking into the cladding from the core are transmitted to form a first light beam, and the amplified signal light in the core of the passive fiber and the pump light leaking into the core from the cladding are transmitted to form a second light beam.

And a substep S12 of irradiating the laser light of the at least one first and second beams onto the surface of the workpiece.

In the embodiment of the invention, the first light beam and the second light beam are transmitted in one optical fiber of the laser, and the energy transmission of the core and the cladding of the optical fiber forms a point-ring-shaped energy distribution mode. A point-ring shape refers to a shape of a circle or circles from a point at the center and around the center, and a typical energy distribution laser of a point-ring shape is a hat-shaped laser.

The proportion of the active fiber that absorbs the pump light is determined by the absorption of the active fiber. In an embodiment of the invention, the absorption of the active fiber can be set to be larger than 0 and smaller than 15dB, so that only a small part of the pump light is absorbed. In one example, the absorption of the active fiber may be set to be greater than 0 and less than 10 dB. In another example, the absorption rate of the active fiber may be set to be greater than 0 and less than 8 dB.

The absorption rate (dB) of the active fiber is determined by the length (m) of the fiber and the absorption coefficient (dB/m) of the fiber itself, so that the absorption rate can be adjusted by setting the length of the active fiber, which is shorter in the embodiment of the present invention compared to the conventional fiber laser. In one example, the length of the active optical fiber may be less than 50 meters. In another example, the length of the active fiber may be less than 30 meters. In another example, the length of the active fiber may be less than 20 meters. In another example, the length of the active fiber may be less than 10 meters. In an embodiment of the present invention, an active optical fiber includes a core and a double or multiple cladding.

Fig. 2 is a schematic diagram of a composite laser energy distribution in an actual state. In an example of the embodiment of the present invention, the energy distribution of the first beam is a flat-top distribution, and the energy of the beam uniformly acts on the surface of the workpiece to perform heat conduction welding on the surface of the workpiece, so that the surface of the workpiece is smooth; however, the energy density of the light beam is low, so that the pinhole effect is not easy to form, and the melting depth is shallow. The energy distribution of the second light beam is Gaussian or Gaussian-like, the energy of the light beam is concentrated, the surface of the workpiece is subjected to deep fusion welding, small holes are easily formed, so that the depth of fusion is large, key holes are formed on the surface of the workpiece, but splashing is easily formed in the process, and the surface forming is influenced. The two kinds of wavelength beams are combined to act on the workpiece, so that respective advantages can be exerted, certain welding seam depth is ensured, splashing is inhibited, and surface forming is improved.

Fig. 3 is a schematic diagram of a composite laser energy distribution in an ideal state. The composite laser comprises a first light beam and a second light beam, wherein the wavelength of the first light beam is different from that of the second light beam. The first light beam surrounds the second light beam and has a ring-shaped cross section. As shown in fig. 3, the first light beam and the second light beam may be closely coupled. The first beam, which may be unabsorbed pump light propagating from the cladding of the active fiber, has a lower power density and a lower brightness than the second beam. In practice, signal light leaking out of the core of the active optical fiber may also be transmitted to the cladding. The power of the first beam is related to the pump power and the active fiber parameters (including core diameter, absorption, doping, length).

The second beam has a cross section of a point, square, circle or similar circle, and can be amplified signal light output from the core of the active optical fiber. In practice, pump light leaking out of the cladding of the active fiber may also be transmitted to the core. The power of the second beam is related to the pump power and the active fiber parameters (including core diameter, numerical aperture NA, absorption, doping, length).

Referring to fig. 4, another schematic diagram of the composite laser energy distribution under ideal conditions is shown. The composite laser comprises a first light beam and a second light beam, wherein the power of the second light beam is larger than that of the first light beam. There is an annular region between the first beam and the second beam, as shown in fig. 4, and the concave portion between the first beam and the second beam is the annular region, and the annular region has no laser radiation or only stray radiation, and thus has no energy or only low energy.

The depressions may be created by fitting a special fiber product, such as a standard QBH energy transmitting fiber. For example, a portion of the QBH energy transmitting fiber is a low index layer doped with F, and dishing occurs in this portion.

Referring to fig. 5, another schematic diagram of the composite laser energy distribution under ideal conditions is shown. The composite laser comprises a first light beam and a second light beam, wherein the power of the second light beam is smaller than that of the first light beam, and a concave part is arranged between the second light beam and the first light beam. The depressed portion between the first beam and the second beam is an annular region, and in the embodiment of the present invention, when the first beam includes a plurality of first beams, the plurality of first beams are sequentially closely connected or an annular region exists between any two adjacent first beams, and the annular region has no laser radiation or only stray radiation.

Referring to fig. 6, another schematic diagram of the composite laser energy distribution under ideal conditions is shown. The composite laser comprises two first beams and one second beam, wherein an annular area exists between the second beam and the first beams, and an annular area also exists between the two first beams.

In one example, the wavelength of the first light beam is different from the wavelength of the second light beam, the central wavelength of the second light beam can be 1030-. In another example, the second beam may have a center wavelength of 1080nm and the first beam may have a center wavelength of 915 nm.

In an embodiment of the invention, the first spot of the first beam and the second spot of the second beam may be controlled to move, during which the first beam preheats the surface of the workpiece to form a melt pool, and the second beam forms a keyhole in the preheated region of the surface of the workpiece.

The first light beam and the second light beam with different wavelengths have different forming characteristics on the surface of the workpiece, and the two light beams with different wavelengths are combined to act on the workpiece, so that respective advantages can be exerted.

When the workpiece is processed, the light spot of the first light beam and the light spot of the second light beam can be controlled to move according to the set track. Because the first light beam surrounds the second light beam, the first light beam can preheat the surface of the workpiece in the moving process in any direction, the absorption rate of the metal workpiece can be greatly improved due to the temperature rise, and the formation of the keyhole by the second light beam in the rear is facilitated more easily. In addition, the first light beam energy behind the welding seam can expand the range of a molten pool in a certain range, and the closing time of the keyhole is prolonged, so that the splashing is reduced.

In the laser processing method of the embodiment of the invention, laser with at least one first beam and one second beam is irradiated on the surface of a workpiece; the first light beam irradiates a workpiece to form a first light spot, the second light beam irradiates the workpiece to form a second light spot, the second light spot is positioned in the first light spot, the surface of the workpiece can be preheated by the first light beam to form a smooth molten pool, and a keyhole is formed on the surface of the workpiece in a preheated area by the second light beam, so that the greater fusion depth is obtained, and the processing effect is good. The two light beams are combined without using an additional composite welding head, so that the processing cost can be reduced. And because the first light beam and the second light beam are transmitted in the same optical fiber, the processing direction principle has no requirement, and the processing technology can be simplified.

When the workpiece is machined, the energy distribution of light spots irradiated to the workpiece by the first light beam can be changed, the energy distribution of light spots irradiated to the workpiece by the second light beam can be changed, and the specific gravity of the characteristics of the light beams with different wavelengths in the welding process is controlled, so that the machining effect of the light beams on the surface of the workpiece is changed.

In one aspect, the energy distribution of the spot illuminated on the workpiece surface can be varied by adjusting the power level of the beam. Specifically, the power value of the first beam may be adjusted to adjust the energy distribution of the spot of the first beam irradiated on the workpiece, and the power value of the second beam may be adjusted to adjust the energy distribution of the spot of the second beam irradiated on the workpiece.

On the other hand, due to the different wavelengths, the first light beam and the second light beam have different focal positions (basically, the positions of the minimum light spots of the light beams with the respective wavelengths) after passing through the focusing optical lens inside the welding head, so that a bifocal distribution of the two wavelengths is formed, and by changing the defocus amount (the position of the workpiece relative to the focal point of the light beams), the energy distribution of the light beams with the two wavelengths on the surface of the workpiece can be adjusted accordingly. For example: when the workpiece is closer to the focus position of the first light beam, the smaller the light spot of the first light beam is, the more obvious the characteristic of the first light beam is; the smaller the spot of the second beam, the more pronounced the characteristics of the second beam as the workpiece is closer to the focal position of the second beam.

The defocus amount of the first beam can be adjusted to adjust the spot profile and spot energy distribution of the first beam onto the workpiece, or the defocus amount of the second beam can be adjusted to adjust the spot profile and spot energy distribution of the second beam onto the workpiece.

For workpieces of different materials, the power value of the first light beam and the power value of the second light beam can be controlled in a quantized mode, and therefore a good machining effect is achieved. For example, taking stainless steel as an example, under the premise of keeping the welding speed and the defocusing amount unchanged, the first beam is not lower than 700 watts, the energy of the second beam is not lower than 500 watts, good surface forming and better spatter control can be obtained, and the molten pool is slightly deepened.

In the embodiment of the invention, the width of the molten pool can be realized by adjusting the energy, the welding speed, the defocusing amount and the like of the laser beam. The width of the molten pool can be changed by limiting certain conditions, such as the welding speed and the energy of the second beam are unchanged, and increasing the energy of the first beam and adjusting the defocusing amount.

In embodiments of the invention, the second beam plays a decisive role in the formation of the keyhole, so that a deeper weld can be obtained by increasing the energy of the second beam. In addition, the depth of the welding seam can be changed by adjusting the defocusing amount of the second light beam and changing the welding speed.

It should be noted that, for simplicity of description, the method embodiments are described as a series of acts or combination of acts, but those skilled in the art will recognize that the present invention is not limited by the illustrated order of acts, as some steps may occur in other orders or concurrently in accordance with the embodiments of the present invention. Further, those skilled in the art will appreciate that the embodiments described in the specification are presently preferred and that no particular act is required to implement the invention.

Referring to fig. 7, a block diagram of a laser processing system of the present invention is shown, which may specifically include a laser 20, a processing head 21;

the laser 20 is configured to provide a composite laser having at least a first beam and a second beam;

The laser machining system may further comprise control means for controlling movement of the spot of the first beam and the spot of the second beam, the first beam preheating a surface of the workpiece to form a melt pool during the movement, and the second beam forming a keyhole in a region of the surface of the workpiece that has been preheated.

The control device can comprise an XYZ three-axis moving assembly, and can respectively control the laser and the processing head to move in an X axis, a Y axis and a Z axis so as to control the spot movement of the output laser.

The first and second beams are both transmitted in one optical fiber of the laser. The optical fiber may be a single-core optical fiber comprising a core and a plurality of claddings, the optical fiber being arranged to provide at least a first light beam propagating in the cladding and a second light beam propagating in the core. Wherein the wavelength of the first light beam may be different from the wavelength of the second light beam. In one example, the central wavelength of the second light beam may be 1030-2140nm, and the central wavelength of the first light beam may be 915-1550 nm. In another example, the first beam may have a center wavelength of 915nm, and the second beam may have a center wavelength of 1080 nm.

In an embodiment of the present invention, the control device is further configured to adjust a power value of the first beam to adjust a spot energy distribution of the first beam irradiated to the workpiece, and/or adjust a power value of the second beam to adjust a spot energy distribution of the second beam irradiated to the workpiece.

In an embodiment of the present invention, the control device is further configured to control the power value of the first light beam and the power value of the second light beam according to a material of the workpiece.

In an embodiment of the present invention, the control device is further configured to adjust the defocus amount of the first beam to adjust the spot profile and energy distribution of the first beam irradiated to the workpiece, or adjust the defocus amount of the second beam to adjust the spot profile and energy distribution of the second beam irradiated to the workpiece.

In an embodiment of the invention, the laser processing head 21 is provided with a single fiber joint, through which an optical fiber of the laser 20 is adapted at the laser processing head 21 to direct the first and second beams onto the workpiece.

Since both the first and second beams are transmitted in one optical fiber, only a single fiber joint is needed to adapt the first and second beams to the laser processing head. Compared with the prior art, the scheme that the double-optical-fiber joint is matched with the laser processing head is needed for transmitting the light beams with two wavelengths in two optical fibers, and the cost is lower.

The laser 20 has a single laser module for transmitting unabsorbed pump light in the fiber cladding to form a first beam and transmitting amplified signal light in the fiber core to form a second beam. Specifically, the single laser module includes an active fiber, the active fiber is used for partially absorbing the pump light and amplifying the signal light, a fiber core of the active fiber is used for transmitting the signal light, a cladding of the active fiber is used for transmitting the pump light which is not absorbed, and a light beam output by the active fiber is transmitted out to obtain the composite laser with the first light beam and the second light beam. Compared with the scheme of generating two wavelength light beams through two laser modules in the prior art, the embodiment of the invention generates the first light beam and the second light beam through the single laser module, and the cost is lower.

The single laser module is also used for transmitting unabsorbed pump light in the optical fiber cladding and signal light leaking into the cladding to form a first light beam, and transmitting the amplified signal light in the optical fiber core and the pump light leaking into the fiber core to form a second light beam.

In an embodiment of the present invention, the laser may be a single cavity resonator laser or a MOPA laser. In the single-cavity laser, the resonant cavity may be formed of fiber bragg gratings FBGs disposed at both ends of an active fiber, and the pump light is transmitted in the resonant cavity and partially absorbed by the active fiber, thereby generating the signal light. In the MOPA laser, a seed light source provides signal light to an active fiber, and the active fiber absorbs pump light to amplify the signal light.

The absorption rate (dB) of the active fiber is determined by the length (m) of the fiber and the absorption coefficient (dB/m) of the fiber itself, so that the absorption rate can be adjusted by setting the length of the active fiber, which is shorter in the embodiment of the present invention compared to the conventional fiber laser. In one example, the length of the active optical fiber may be less than 50 meters. In another example, the length of the active fiber may be less than 30 meters. In another example, the length of the active fiber may be less than 20 meters. In another example, the length of the active fiber may be less than 10 meters.

Fig. 8 is a structural diagram of a laser in an embodiment of the present invention. Wherein the laser may include: a pumping assembly 1 for providing pumping light, an active optical fiber 2, an optical fiber output device 3; the active fiber 2 is used for partially absorbing the pump light and amplifying the signal light, the core of the active fiber 2 is used for transmitting the signal light, and the cladding of the active fiber 2 is used for transmitting the pump light which is not absorbed; and transmitting the light beam output by the active optical fiber 2 to obtain the composite laser with at least one first light beam and one second light beam.

The laser of the embodiment of the invention can be a laser with an all-fiber structure, namely, devices in the laser are connected through optical fibers or are connected with the optical fibers.

The pump assembly 1 may include a plurality of pump light sources 11 and a beam combiner 12. The output power of the pump light source 11 can be adjusted to adjust the power of the pump light input into the active fiber 2 to form composite laser spot outputs with different energy ratio profiles.

The combiner 12 may be a high power N + 1: the beam combiner 1 comprises a plurality of input optical fibers and an output optical fiber, wherein each pump light source 11 can be connected with one input optical fiber, and the pump light output by the plurality of pump light sources 11 is coupled and output from the output optical fiber by the beam combiner 12.

The pump light source 11 may be a semiconductor pump light source, or may be a laser light source output by any optical fiber. For example, the plurality of pump light sources 11 may include at least one of a semiconductor laser, a direct semiconductor laser, and a short wavelength fiber laser. For example, the plurality of pump light sources may all be semiconductor lasers, or a part of the pump light sources may be direct semiconductor lasers, and the remaining part of the pump light sources may be short-wavelength fiber lasers. The kind of the pumping light source can be set according to actual needs.

In the embodiment of the present invention, the wavelength of the second beam and the wavelength of the first beam of the composite laser may be set according to the wavelength of the pump light source 11 and the doping element of the active fiber 2. The doping element may include ytterbium (Yb), erbium (Er), thulium (Tm), and the like.

For example, the pumping wavelength is 915nm, the active optical fiber is doped with Yb, the wavelength of the signal light can be in the range of 1030-1090 nm, the wavelength of the second light beam can be in the range of 1030-1090 nm, the wavelength bandwidth range is 0.5 nm-20 nm, and the power is not less than 100W; the wavelength of the first light beam comprises 915 nm.

The plurality of pump light sources 11 may be pump light sources of the same wavelength or pump light sources of different wavelengths. Using pump light sources 11 of different wavelengths, composite lasers of different wavelength combinations can be generated.

In the embodiment of the present invention, a control device connected to the pump light source 11 may be further included, and the control device is configured to adjust the power of the pump light to form a composite laser spot output with different energy ratio profiles.

The control device can control the pump light power output by each pump light source 11. For example, the control device controls a part of the pump light source 11 to be turned on or off, and controls a part of the pump light source 11 to increase or decrease the output pump light power.

In the embodiment of the present invention, the active optical fiber 2 may be a double-clad or multi-clad active optical fiber, and the optical fiber output device 4 may include a double-clad or multi-clad first optical fiber and an output head.

In the embodiment of the present invention, the cladding of the first optical fiber is used for transmitting the pump light which is not absorbed in the active optical fiber 2, and the core of the first optical fiber is used for transmitting the signal light in the active optical fiber 2.

In the embodiment of the present invention, the cladding of the first optical fiber is used for transmitting the pump light that is not absorbed in the active optical fiber 2 and the signal light leaking into the cladding, and the core of the first optical fiber is used for transmitting the signal light in the active optical fiber 2 and the pump light leaking into the core.

The numerical aperture of the core of the active fiber 2 and the numerical aperture of the core of the first fiber are designed to control part of the signal light to enter the cladding, so that the laser transmission mode of the core of the active fiber 2 is the same as that of the core of the first fiber.

The numerical aperture of the cladding of the active fiber 2 and the numerical aperture of the cladding of the first fiber are designed to control part of the pump light to enter the fiber core, so that the laser transmission mode of the cladding of the active fiber 2 is the same as the laser transmission mode of the corresponding cladding in the first fiber.

The cladding of a multi-clad optical fiber can be divided into an inner cladding and an outer cladding. For double-clad fibers, the cladding near the core is the inner cladding and the cladding far from the core is the outer cladding. For multi-clad fibers with more than three claddings, the cladding furthest from the fiber is the outer cladding and the remaining claddings are the inner cladding. The outer cladding is typically a low index material and is not used to transmit laser light.

In the embodiment of the present invention, among the plurality of claddings of the active fiber 2, a cladding other than the outer cladding may be used to transmit the pump light that is not absorbed. Among the plurality of claddings of the multi-clad first optical fiber, a cladding other than the outer cladding is used for transmitting the pump light which is not absorbed.

In one example, the number of claddings of the active fiber 2 may be the same as the number of claddings of the first fiber.

In another example, the number of claddings of the active fiber 2 may be less than that of the first fiber, in which case the active fiber 2 and the first fiber are matched by tapering or direct fusion splicing, so that the cladding light transmitted in the cladding of the active fiber 2 can enter the specific cladding of the first fiber according to the design requirement. For example, the active fiber is double-clad and the first fiber is four-clad. The laser light transmitted from the cladding of the active optical fiber 2 may be diffused into at least one cladding of the first optical fiber to be transmitted. Specifically, the active fiber and the first fiber can be individually tapered through the fiber cladding or simultaneously tapered through the cladding and the fiber core to match the fiber size and the NA setting, so that the pump light transmitted in the active fiber cladding can enter at least one cladding of the first fiber.

In an embodiment of the present invention, the optical fiber output device may further include a stripper; the stripper is used for stripping the laser transmitted in the outermost layer or the outermost multiple layers of cladding of the first optical fiber, and can specifically strip unwanted cladding light according to actual needs.

In an embodiment of the present invention, the laser may further include: a second optical fiber 4 connected between the active optical fiber 2 and the fiber output device 3, and a third optical fiber 5 connected between the combiner 12 and the active optical fiber 2. The first, second and third

optical fibers

4, 5 are all passive fibers.

The second 4 and third 5 optical fibers may be double-clad or multi-clad fibers, the second optical fiber 4 being matched to the active fiber 2 and the first optical fiber of the fiber output device 3. Specifically, the core of the second optical fiber 4 may be used to transmit signal light, and the cladding of the second optical fiber 4 may be used to transmit unabsorbed pump light. The core of the second optical fiber 4 is also used for transmitting the pump light leaking into the core, and the cladding of the second optical fiber 4 is also used for transmitting the signal light leaking into the cladding.

In an embodiment of the present invention, the spot parameters (including spot size and spot shape) of the second beam of the composite laser are related to core parameters of the active fiber and core parameters of the passive fiber. Wherein the core parameters include numerical aperture NA.

In an embodiment of the invention, the spot parameters (including spot shape and spot size) of the first beam of the composite laser are related to the cladding diameter and numerical aperture NA of the second optical fiber 4 and the first optical fiber, and the combiner parameters.

The beam combiner parameters refer to technological parameters for manufacturing the beam combiner, the beam combiner is manufactured according to the input optical fiber and the output optical fiber to be connected when being manufactured, and the manufacturing technological parameters are set according to the input optical fiber and the output optical fiber to be connected. In the embodiment of the present invention, the beam combiner parameter may be set according to the input fiber connecting the pump light source and the third fiber 5, so that the influence of the third fiber 5 on the output laser may be summarized to the beam combiner parameter, and the beam combiner parameter may include the parameter of the input fiber of the pump light source and the parameter of the third fiber 5.

In practice, the cladding diameter, the numerical aperture NA, the beam combiner parameter, and the first fiber parameter of the second fiber 4 may be set according to actual requirements, so as to set the spot parameter of the first beam of the output composite laser. The second optical fiber 4 may be provided with the same fiber parameters as the third optical fiber 5.

In an example of the embodiment of the present invention, the laser may further include: a fiber bragg grating FBG6 arranged at both ends of said active fiber forming a resonant cavity. Referring to fig. 9, a block diagram of a laser in one example is shown.

Wherein, fiber bragg grating FBG6 may include HR (High Reflector) FBG and OC (Out Coupler) FBG, the HR FBG is disposed between the pumping assembly 1 and the active fiber 2, the OC FBG is disposed between the active fiber 2 and the fiber output device 3, and the HR FBG and the OC FBG constitute a resonant cavity. The pump light is transmitted in the cavity, and a portion is absorbed by the active fiber 2 to generate signal light, and another portion is output from the cavity. The fiber output device 3 outputs the laser light output from the resonator.

In another example of the embodiment of the present invention, the laser may further include: a seed light source for providing signal light. Referring to fig. 10, a block diagram of a laser in another example is shown. The signal light output by the seed light source 7 and the pump light output by the pump assembly 1 are transmitted to the active optical fiber 2 in a coupling mode, and the active optical fiber 2 absorbs the pump light to amplify the signal light.

A laser that supplies signal light through a seed light source may be referred to as a MOPA (Master Oscillator Power-Amplifier) laser.

In this example, each of the pump light source 11 and the seed light source 7 may be respectively connected to one input fiber of the beam combiner 12, and the pump light output by the plurality of pump light sources and the signal output by the seed light source 7 are optically coupled by the beam combiner 12 and output from the output fiber of the beam combiner 12 to the active fiber 2.

The pump light and the signal light output from the output fiber of the beam combiner 12 may be received by the active fiber 2, and the pump light is absorbed by the active fiber 2 to amplify the signal light.

In an alternative embodiment, the length of the active fiber may be set to 0, i.e. a structure is formed to directly output the signal light and the pump light by using a combiner, and the final spot output characteristics are selected by different matching of the output fiber and the combiner.

The seed light source 7 may comprise a single-cavity fiber laser, or a fiber-coupled thin-film laser, or a diode-pumped solid-state laser (e.g., a Nd-YAG laser), or a semiconductor laser.

In this example, a control device is also included in communication with the seed light source for adjusting the output power of the seed light source to form a composite laser spot output of different energy ratio profiles.

In this example, the wavelength of the second beam and the wavelength of the first beam may be set according to the wavelength of the seed light source 7, the wavelength of the pump light source 11, and the doping element of the active optical fiber 2.

The power of the second beam is related to the power of the seed light source, the pump power and the parameters of the active fiber (including core diameter, numerical aperture NA, absorption rate, doping material, length).

In practical use, because the parameters of the active optical fiber are fixed, the power of the second light beam and the power of the first light beam can be adjusted by independently and continuously adjusting the power of the seed light source or the pumping power, so that light spot outputs with different energy proportion profiles are formed.

In one example, the wavelengths of the pump light and the signal light are different, the central wavelength of the signal light may be 1030-2140nm, and the central wavelength of the pump light may be 915-1550 nm. In another example, the central wavelength of the signal light may be 1080nm and the central wavelength of the pump light may be 915 nm.

In embodiments of the present invention, the laser processing system may be used for laser welding, laser cladding or other laser applications, further laser welding being laser continuous welding. Laser continuous welding is a processing mode different from spot welding, and a laser processing system can continuously output laser to process a workpiece.

The laser processing system of the embodiment of the invention can utilize the same optical fiber of the laser to output the first light beam and the second light beam to process the workpiece, preheat the surface of the workpiece by utilizing the first light beam to form a smoother molten pool, and form a keyhole in a preheated area on the surface of the workpiece by utilizing the second light beam to obtain larger fusion depth. The two light beams are combined without using an additional composite welding head, so that the processing cost is reduced.

The embodiments in the present specification are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, apparatus, or computer program product. Accordingly, embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, terminal devices (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing terminal to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing terminal to cause a series of operational steps to be performed on the computer or other programmable terminal to produce a computer implemented process such that the instructions which execute on the computer or other programmable terminal provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications of these embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the embodiments of the invention.

Finally, it should also be noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or terminal that comprises the element.

The laser processing method and the laser processing system provided by the invention are described in detail, and the principle and the implementation mode of the invention are explained by applying specific examples, and the description of the examples is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. A laser processing system for generating composite laser light for output to a workpiece, comprising a laser and a laser processing head;

2. The laser machining system of claim 1, further comprising a control device for adjusting the power of the first beam to adjust the spot energy distribution of the first beam to the workpiece and/or adjusting the power of the second beam to adjust the spot energy distribution of the second beam to the workpiece.

3. The laser machining system of claim 2 wherein the control means is further configured to control the power level of the first beam and the power level of the second beam based on the material of the workpiece.

4. The laser processing system of claim 2, wherein the control device is further configured to adjust the defocus amount of the first beam to adjust the spot profile and energy distribution of the first beam onto the workpiece, or to adjust the defocus amount of the second beam to adjust the spot profile and energy distribution of the second beam onto the workpiece.

5. A laser machining system according to claim 1 wherein the laser machining head is provided with a single fibre splice through which the fibre of the laser is adapted at the laser machining head to direct the first and second beams onto the workpiece.

6. The laser processing system of claim 1, wherein the laser has a single laser module configured to transmit unabsorbed pump light and signal light leaking into a cladding of the fiber to form a first beam and to transmit amplified signal light in a core of the fiber and pump light leaking into the core to form a second beam.

7. The laser processing system of claim 6, wherein the single laser module is further configured to transmit unabsorbed pump light in a cladding of the optical fiber and signal light leaking into the cladding to form a first beam and transmit amplified signal light in a core of the optical fiber and pump light leaking into the core to form a second beam.

8. The laser processing system of claim 1, wherein the laser is a single cavity or MOPA laser.

9. The laser processing system as claimed in claim 1, wherein the wavelength of the first beam is different from the wavelength of the second beam, the central wavelength of the second beam is 1030-2140nm, and the central wavelength of the first beam is 915-1550 nm.

10. The laser machining system of claim 1, wherein the first beam has a center wavelength of 915nm and the second beam has a center wavelength of 1080 nm.

11. A laser processing method, comprising:

12. The method of claim 110, wherein the energy distribution of the first beam is flat-topped and the energy distribution of the second beam is gaussian.

13. The method of claim 11, further comprising:

and adjusting the power value of the first light beam to adjust the energy distribution of the light spot irradiated to the workpiece by the first light beam, and/or adjusting the power value of the second light beam to adjust the energy distribution of the light spot irradiated to the workpiece by the second light beam.

14. The method of claim 11, further comprising:

and controlling the power value of the first light beam and the power value of the second light beam according to the material of the workpiece.

15. The method of claim 11, further comprising:

and adjusting the defocusing amount of the first light beam to adjust the spot profile and the energy distribution of the first light beam irradiated to the workpiece, or adjusting the defocusing amount of the second light beam to adjust the spot profile and the energy distribution of the second light beam irradiated to the workpiece.

16. The method of claim 11, wherein said irradiating laser light having at least a first beam and a second beam onto a surface of a workpiece comprises:

17. The method of claim 11, wherein said irradiating laser light having at least a first beam and a second beam onto a surface of a workpiece comprises:

18. The method as claimed in claim 11, wherein the wavelength of the first light beam is different from the wavelength of the second light beam, the central wavelength of the first light beam is 915-1550nm, and the central wavelength of the second light beam is 1030-2140 nm.

19. The method of claim 11, wherein the first beam has a center wavelength of 915nm and the second beam has a center wavelength of 1080 nm.